Foix-Alajouanine Syndrome

Foix-Alajouanine syndrome (subacute necrotising myelopathy) is progressive thrombotic or ischaemic cord necrosis from a venous outflow problem, classically associated with a spinal dural arteriovenous fistula or other spinal vascular malformation. It affects mainly men aged 40 to 60 years, with thoracolumbar cord involvement.

Pathophysiology. Chronic venous hypertension causes cord congestion and ischaemia, and thrombosis of draining veins leads to venous infarction and necrosis of the lower cord.

Subacute progressive paraparesis (upper then lower motor neuron signs), sensory loss, severe back or leg pain, bladder and bowel dysfunction, with flaccid paralysis and areflexia as the lower cord necroses. Deterioration is rapid over weeks, with stepwise worsening, and the condition may follow exertion or steroid treatment.

Red flags.

• Rapidly progressive paraplegia with flaccid features.
• Worsening after corticosteroids.

MRI of the spine shows long segment T2 hyperintensity of the lower cord and conus with swelling, serpentine perimedullary flow voids and patchy enhancement. Spinal digital subtraction angiography is the definitive test and locates the fistula. CSF protein is raised, often markedly. Exclude myelitis, tumour and cord infarction.

Differential diagnosis.

• Transverse myelitis and neuromyelitis optica spectrum disorder.
• Spinal cord tumour, anterior spinal artery infarct and compressive myelopathy.
• Guillain-Barre syndrome and epidural abscess.

Fistula or malformation. Urgent occlusion: endovascular embolisation (liquid embolic agent) or surgical disconnection of the draining vein. Early treatment before necrosis offers the best chance of recovery. Established necrosis is irreversible.

Avoid corticosteroids (can worsen venous congestion), hypotension and dehydration.

Anticoagulation. Not usually given for thrombosis in this condition without specialist advice because of haemorrhage risk. Give prophylactic enoxaparin 40 mg SC daily when immobile (20 mg if creatinine clearance is under 30 mL/min).

Rehabilitation. Physiotherapy, bladder and bowel care, pressure care, spasticity treatment and psychological support.

Prognosis. Poor when treatment is late, with severe permanent disability.

Monitoring. Neurological state, MRI and angiography after treatment.

Referral and escalation. Refer as an emergency to neurosurgery and neuroradiology.